Analog manufacturing is moving towards, and is expected to one day be consumed, by digital manufacturing. This shift is customer driven and arises from a desire for more customized products, on-demand delivery, and other market factors that support the move towards a less expensive alternative to traditional manufacturing.
Digital fabrication encompasses a range of technologies, including ink jet. Ink jet has the advantage of being a non-contact, additive process (as opposed to subtractive processes like computer numerical control machining) with the built-in ability to deliver metered amounts of various fluids to a precise location in time and space. Moreover, digital ink jet fabrication has a wide materials scope and may be used to print a variety of materials, such as UV-curable resins and molten thermoplastic polymers.
Current technologies for three-dimensional printing include stereolithography and rapid prototyping. While suitable for some purposes, these technologies each have their own limitations. Stereolithography is a costly process with machines often costing in excess of $250,000. The polymer materials employed are also extremely expensive, with a common stereolithography photopolymer costing about $800 per gallon. Rapid prototyping systems typically use a fused deposition method wherein molten acrylonitrile-butadiene-styrene (ABS) polymer is deposited. The extremely rapid solidification of the ABS manifests in ridges that form on the finished object. Post-printing treatment of the prototype (such as sanding or polishing) is required to render a smooth object.
The concept of “freezing” or phase-change has been described for three-dimensional printing using aqueous inks on a chilled (that is, sub-zero temperature) substrate. See D. Mager et al., “Phase Change Rapid Prototyping With Aqueous Inks,” NIP 23 and Digital Fabrication 2007 Conference Proceedings, pages 908-911, which is hereby incorporated by reference herein. Ink jet fabrication using wax based materials has been described but is disadvantaged by the fact that the resulting primary structures are neither robust nor permanent.
Currently, many three-dimensional printing technologies use rigid materials. For example, fused deposition methods use molten thermosetting resins, such as ABS plastic and hard acrylates. Moreover, many current technologies use ultra-thin jetted layers (for example, 0.6 mm) that must be cured after each deposition step. As such, there remains a need for a wider selection of materials having a variety of different properties, particularly a wider range of room temperature modulus, thereby providing rigid and rubbery objects, and materials that reduce the number of curing steps between deposition steps, thereby providing faster object construction and lower energy requirements.